From the article: Though his father’s family had come from an area about 50 miles away, Mr. Reyes was an outsider in the Copper Canyon, among the mountains of the Sierra Madre Occidental. He found the Tarahumara, who are known for their running prowess, living lives not wholly unlike their ancestors centuries ago, who fled to these elevations from the Spanish.

“They still had their own culture,” Mr. Reyes said. “It wasn’t Mexicanized.”

However, by the time he returned for several months in 2009 to photograph, Mr. Reyes saw signs of a cultural shift among the Tarahumara (also known as the Rarámuri). Men who had previously worn loincloths now wore jeans. Children, most of them now in school, were speaking Spanish, while their grandparents spoke only Tarahumara. People were leaving the canyon to seek work in the cities.

Mr. Reyes did not photograph or see anyone consuming iskiate during his visit.